No top end

Stang_Crazy · 02-14-2001, 03:27 PM

As you can see from my signature, my mhp is low for my time. I don't know why my car is such a dog at high speeds. From 0-60 I can hang with alot of people but after 60, I just wave as they blow by me. The stall on my converter is around 2400-2600 if I remember correctly. Could this be the problem? Am I just not making enough power to take advantage of the stall speed?

------------------
91 GT AOD
Ultra Blue Metallic
3.73's, flows,
PI Converter, 14.71@91.78mph
2.11 60'

Godslayer · 02-14-2001, 05:40 PM

You got a 14.7 at 91MPH? Wow I can't even break 15 usually at 95

Damn I need gears hehe. Anyway.. have you considered the possibility that you are losing fuel or pressure at high RPM? The stall speed wouldn't matter at high speed, it's for launching. If it's possible hook a FP guage to the rail and route it so you can see it when you are driving fast under load (accelerating) and see if it drops. This would be my first step. The fuel pump might be going south especially if it's original.

------------------
87 GT
Full exhaust, K&N, KB Subs, BBK STB, homeade dumps...

87 Taurus
New York
Winters Bite!

QuantumMotorsports · 02-14-2001, 06:09 PM

What kind of exhaust do you have? Are you running stock headers? H pipe with converters? pipes over the axle to tips or do you have turndowns? Open exhaust will help with high end power. What have you had done to the tranny? I don't know if that could be it. I think the fuel pressure idea is a good one too. Check that out. About the exhaust though, I was running with pipes over the axles like on LX mustangs and running 15.4 and now I have turndowns and am beating cars that normally run 14.50s. Still haven't been to the track yet to see, but think it's much faster now.

------------------
Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny
15.43 @ 91.08mph (not shabby for a 3600 pound car)
60' 2.453 Street tires suck!!!

Unit 5302 · 02-15-2001, 12:28 AM

What kind of timing and fuel are you running? If the engine begins to knock at higher rpms the computer may be pulling out timing or something too.

When's the last time you've done a tuneup?

MiracleMax · 02-15-2001, 12:54 AM

Hey who cloned my car! My engine had an intake leak and goofy factory machining plus a burnt up AOD

Stang_Crazy · 02-15-2001, 12:03 PM

My car has 86k on it and the last time I did a tune up was last spring. I only have flowmaster american thunder mufflers. The pipes do go over the axle and exit through the back though. I have a friend that just put turn-downs on his car and it seemed to help. Still have the old, rusty, factory headers and I still have the original h-pipe with cats. I was thinking about getting headers and a (legal) h-pipe this spring so that would complete my exhaust.

I'm pretty sure the fuel pump is original so that may have to go as well. I'll check the fuel pressure and see if it is the problem. Oh yea, I don't know what my timing is at because I never had it bumped up. Gotta find someone with a gun that will do it...

------------------
91 GT AOD
Ultra Blue Metallic
3.73's, flows,
PI Converter, 14.71@91.78mph
2.11 60'

2FastLX · 02-15-2001, 12:17 PM

My car was the same way. It would begin to lose all of its power at 4000rpm and would barely make it to 4500. After putting on my L/T's, Pro Chamber crossover, and cat-back it climbs hard all the way to 6000rpms and acts like it would go all the way to 7500rpm or so if it wasn't for the rev limiter.

If you can get your cat pipe removed easy enough (those bolts are a &!+$# to break lose sometimes) you can see if that is your problem. If you can't see light through the cats they're plugged. You can also take it for a spin with open headers and see how well it climbs without the cats =)

QuantumMotorsports · 02-15-2001, 12:25 PM

I wouldn't take it up to high RPMs with open headers. Two things, O2 sensors, it'll run lean as hell because the sensors won't heat up enough because of the open exhaust. And you could burn up an exhaust valve because of no back pressure. But I would recommend getting rid of the stock H pipe. At least get one with high flow cats. And get turn downs. Just that exhaust work will help it climb to high RPMs. Also, check the timing. If it is either too far advanced or not advanced enough it could cause high end bogging either because of pinging, or just not enough advance. Timing makes a huge difference in your power, if it's not timed properly, you're wasting power and performance suffers badly.

------------------
Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny
15.43 @ 91.08mph (not shabby for a 3600 pound car)
60' 2.453 Street tires suck!!!

1989GT · 02-15-2001, 01:53 PM

Ahhh don't you just love stock heads.

Opening up the exhaust will help a lot. Bump that timing. When I did mine I waited because I didn't have a timing light. Well when I finally set it, it was set at like 6* advanced. Needless to say when I bumped it to 14* I say a big improvement. When mt car was stock it would fly thru 1st and 2nd but 3rd just lacked something....heads and intake took care of that.

------------------
89GT,T-5Z, D.S.S. 306 shortblock w\main support, B-303 cam, Cobra intake, GT40P heads, 1.72rr, MAC "P" headers, MAC off-road H-Pipe, MAC true-fit w\tips, 373's...and the list goes on!
Throttle Junkie Powered by Ford!
12.824 @ 107.05 MPH
PVT Blankenship leaving for BCT 14MAR01
MOS 67 Romeo

02-14-2001, 03:27 PM	#1
Stang_Crazy It's never clean enough! Join Date: Jan 1999 Location: Shaler, PA Posts: 1,542	No top end As you can see from my signature, my mhp is low for my time. I don't know why my car is such a dog at high speeds. From 0-60 I can hang with alot of people but after 60, I just wave as they blow by me. The stall on my converter is around 2400-2600 if I remember correctly. Could this be the problem? Am I just not making enough power to take advantage of the stall speed? ------------------ 91 GT AOD Ultra Blue Metallic 3.73's, flows, PI Converter, 14.71@91.78mph 2.11 60'

02-14-2001, 05:40 PM	#2
Godslayer Registered Member Join Date: Mar 1999 Location: Largo, FL USA Posts: 274	You got a 14.7 at 91MPH? Wow I can't even break 15 usually at 95 Damn I need gears hehe. Anyway.. have you considered the possibility that you are losing fuel or pressure at high RPM? The stall speed wouldn't matter at high speed, it's for launching. If it's possible hook a FP guage to the rail and route it so you can see it when you are driving fast under load (accelerating) and see if it drops. This would be my first step. The fuel pump might be going south especially if it's original. ------------------ 87 GT Full exhaust, K&N, KB Subs, BBK STB, homeade dumps... 87 Taurus New York Winters Bite!

02-14-2001, 06:09 PM	#3
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	What kind of exhaust do you have? Are you running stock headers? H pipe with converters? pipes over the axle to tips or do you have turndowns? Open exhaust will help with high end power. What have you had done to the tranny? I don't know if that could be it. I think the fuel pressure idea is a good one too. Check that out. About the exhaust though, I was running with pipes over the axles like on LX mustangs and running 15.4 and now I have turndowns and am beating cars that normally run 14.50s. Still haven't been to the track yet to see, but think it's much faster now. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny 15.43 @ 91.08mph (not shabby for a 3600 pound car) 60' 2.453 Street tires suck!!!

02-15-2001, 12:28 AM	#4
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	What kind of timing and fuel are you running? If the engine begins to knock at higher rpms the computer may be pulling out timing or something too. When's the last time you've done a tuneup?

02-15-2001, 12:54 AM	#5
MiracleMax Registered Member Join Date: Apr 1999 Location: Hayes, Va, USA Posts: 798	Hey who cloned my car! My engine had an intake leak and goofy factory machining plus a burnt up AOD

02-15-2001, 12:03 PM	#6
Stang_Crazy It's never clean enough! Join Date: Jan 1999 Location: Shaler, PA Posts: 1,542	My car has 86k on it and the last time I did a tune up was last spring. I only have flowmaster american thunder mufflers. The pipes do go over the axle and exit through the back though. I have a friend that just put turn-downs on his car and it seemed to help. Still have the old, rusty, factory headers and I still have the original h-pipe with cats. I was thinking about getting headers and a (legal) h-pipe this spring so that would complete my exhaust. I'm pretty sure the fuel pump is original so that may have to go as well. I'll check the fuel pressure and see if it is the problem. Oh yea, I don't know what my timing is at because I never had it bumped up. Gotta find someone with a gun that will do it... ------------------ 91 GT AOD Ultra Blue Metallic 3.73's, flows, PI Converter, 14.71@91.78mph 2.11 60'

02-15-2001, 12:17 PM	#7
2FastLX The Photoshop Guru Join Date: Feb 2001 Location: Mecca, Indiana Posts: 1,419	My car was the same way. It would begin to lose all of its power at 4000rpm and would barely make it to 4500. After putting on my L/T's, Pro Chamber crossover, and cat-back it climbs hard all the way to 6000rpms and acts like it would go all the way to 7500rpm or so if it wasn't for the rev limiter. If you can get your cat pipe removed easy enough (those bolts are a &!+$# to break lose sometimes) you can see if that is your problem. If you can't see light through the cats they're plugged. You can also take it for a spin with open headers and see how well it climbs without the cats =)

02-15-2001, 12:25 PM	#8
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	I wouldn't take it up to high RPMs with open headers. Two things, O2 sensors, it'll run lean as hell because the sensors won't heat up enough because of the open exhaust. And you could burn up an exhaust valve because of no back pressure. But I would recommend getting rid of the stock H pipe. At least get one with high flow cats. And get turn downs. Just that exhaust work will help it climb to high RPMs. Also, check the timing. If it is either too far advanced or not advanced enough it could cause high end bogging either because of pinging, or just not enough advance. Timing makes a huge difference in your power, if it's not timed properly, you're wasting power and performance suffers badly. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny 15.43 @ 91.08mph (not shabby for a 3600 pound car) 60' 2.453 Street tires suck!!!

02-15-2001, 01:53 PM	#9
1989GT Registered Member Join Date: Apr 1999 Location: Cincinnati,OH Posts: 1,511	Ahhh don't you just love stock heads. Opening up the exhaust will help a lot. Bump that timing. When I did mine I waited because I didn't have a timing light. Well when I finally set it, it was set at like 6* advanced. Needless to say when I bumped it to 14* I say a big improvement. When mt car was stock it would fly thru 1st and 2nd but 3rd just lacked something....heads and intake took care of that. ------------------ 89GT,T-5Z, D.S.S. 306 shortblock w\main support, B-303 cam, Cobra intake, GT40P heads, 1.72rr, MAC "P" headers, MAC off-road H-Pipe, MAC true-fit w\tips, 373's...and the list goes on! Throttle Junkie Powered by Ford! 12.824 @ 107.05 MPH PVT Blankenship leaving for BCT 14MAR01 MOS 67 Romeo